Actually lookleft they probably enjoy it. Breaks the monotony of the 99.9% of those who don't question the procedure. I think you will find it is only a frisk search you can request in a private room. One reason for bag searches is due to the clutter of leads, cables and portable electronic items that the operator cannot clear on the first run.
The reason they also pay attention to batteries, aerosols etc is that as employees of an airline or airport operator they have an obligation under the CASA regs for dangerous goods.